全文获取类型
收费全文 | 16084篇 |
免费 | 1320篇 |
国内免费 | 771篇 |
专业分类
电工技术 | 1621篇 |
技术理论 | 2篇 |
综合类 | 2280篇 |
化学工业 | 1484篇 |
金属工艺 | 581篇 |
机械仪表 | 939篇 |
建筑科学 | 2298篇 |
矿业工程 | 538篇 |
能源动力 | 470篇 |
轻工业 | 616篇 |
水利工程 | 673篇 |
石油天然气 | 511篇 |
武器工业 | 142篇 |
无线电 | 1585篇 |
一般工业技术 | 1016篇 |
冶金工业 | 782篇 |
原子能技术 | 123篇 |
自动化技术 | 2514篇 |
出版年
2024年 | 48篇 |
2023年 | 121篇 |
2022年 | 212篇 |
2021年 | 242篇 |
2020年 | 288篇 |
2019年 | 263篇 |
2018年 | 236篇 |
2017年 | 321篇 |
2016年 | 371篇 |
2015年 | 438篇 |
2014年 | 861篇 |
2013年 | 697篇 |
2012年 | 946篇 |
2011年 | 1107篇 |
2010年 | 972篇 |
2009年 | 1012篇 |
2008年 | 1003篇 |
2007年 | 1195篇 |
2006年 | 1171篇 |
2005年 | 981篇 |
2004年 | 972篇 |
2003年 | 892篇 |
2002年 | 776篇 |
2001年 | 644篇 |
2000年 | 491篇 |
1999年 | 416篇 |
1998年 | 290篇 |
1997年 | 219篇 |
1996年 | 168篇 |
1995年 | 121篇 |
1994年 | 98篇 |
1993年 | 107篇 |
1992年 | 86篇 |
1991年 | 63篇 |
1990年 | 67篇 |
1989年 | 50篇 |
1988年 | 41篇 |
1987年 | 23篇 |
1986年 | 30篇 |
1985年 | 19篇 |
1984年 | 19篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1979年 | 7篇 |
1977年 | 5篇 |
1973年 | 5篇 |
1968年 | 6篇 |
1966年 | 4篇 |
1958年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
《Ceramics International》2022,48(11):15056-15063
Hydrogen (H2) sensors based on metal oxide semiconductors (MOS) are promising for many applications such as a rocket propellant, industrial gas and the safety of storage. However, poor selectivity at low analyte concentrations, and independent response on high humidity limit the practical applications. Herein, we designed rGO-wrapped SnO2–Pd porous hollow spheres composite (SnO2–Pd@rGO) for high performance H2 sensor. The porous hollow structure was from the carbon sphere template. The rGO wrapping was via self-assembly of GO on SnO2-based spheres with subsequent thermal reduction in H2 ambient. This sensor exhibited excellently selective H2 sensing performances at 390 °C, linear response over a broad concentration range (0.1–1000 ppm) with recovery time of only 3 s, a high response of ~8 to 0.1 ppm H2 in a minute, and acceptable stability under high humidity conditions (e. g. 80%). The calculated detection limit of 16.5 ppb opened up the possibility of trace H2 monitoring. Furthermore, this sensor demonstrated certain response to H2 at the minimum concentration of 50 ppm at 130 °C. These performances mainly benefited from the special hollow porous structure with abundant heterojunctions, the catalysis of the doped-PdOx, the relative hydrophobic surface from rGO, and the deoxygenation after H2 reduction. 相似文献
2.
ABSTRACTIn this paper, we review some algebraic control system. Precisely, linear and bilinear systems on Euclidean spaces and invariant and linear systems on Lie groups. The fourth classes of systems have a common issue: to any class, there exists an associated subgroup. From this object, we survey the controllability property. Especially, from those coming from our contribution to the theory. 相似文献
3.
《Intermetallics》2015
Fine-grained fully-lamellar (FL) microstructure is desired for TiAl components to serve as compressor/turbine blades and turbocharger turbine wheels. This study deals with the process and phase transformation to produce FL microstructure for Mo stabilized beta-gamma TiAl alloys without single α-phase field. Unlike the α + γ two-phased TiAl or beta-gamma TiAl with single α-phase field, the wrought multi-phase TiAl–4/6Nb–2Mo–B/Y alloys exhibit special annealing process to obtain FL microstructure. Short-term annealing at temperatures slightly above β-transus is recommended to produce the desired FL microstructure. The related mechanism is to guarantee the sufficient diffusion homogenization of β stabilizers during single β-phase annealing, and further avoid α decomposition by α → γ + β when cooling through α + β + γ phase field. The colony boundary β phase contributes to fine-grained nearly FL microstructure, by retarding the coarsening of the α phase grains. 相似文献
4.
1-read/1-write (1R1W) register file (RF) is a popular memory configuration in modern feature rich SoCs requiring significant amount of embedded memory. A memory compiler is constructed using the 8T RF bitcell spanning a range of instances from 32 b to 72 Kb. An 8T low-leakage bitcell of 0.106 μm2 is used in a 14 nm FinFET technology with a 70 nm contacted gate pitch for high-density (HD) two-port (TP) RF memory compiler which achieves 5.66 Mb/mm2 array density for a 72 Kb array which is the highest reported density in 14 nm FinFET technology. The density improvement is achieved by using techniques such as leaf-cell optimization (eliminating transistors), better architectural planning, top level connectivity through leaf-cell abutment and minimizing the number of unique leaf-cells. These techniques are fully compatible with memory compiler usage over the required span. Leakage power is minimized by using power-switches without degrading the density mentioned above. Self-induced supply voltage collapse technique is applied for write and a four stack static keeper is used for read Vmin improvement. Fabricated test chips using 14 nm process have demonstrated 2.33 GHz performance at 1.1 V/25 °C operation. Overall Vmin of 550 mV is achieved with this design at 25 °C. The inbuilt power-switch improves leakage power by 12x in simulation. Approximately 8% die area of a leading 14 nm SoC in commercialization is occupied by these compiled RF instances. 相似文献
5.
6.
7.
进入21世纪,随着集成电路的发展,SoC(System on Chip)片上系统应运而生。而作为SoC重要组成部分的嵌入式存储器,在SoC中所占的比重正逐步增加,并起着越来越重要的作用,那么嵌入式存储器与独立的存储器芯片在设计上存在着哪些差异?对此本文将以NOR型闪存为例在制造工艺的选取、衍生产品的设计、功耗与噪声、后端功能仿真、测试与修复等方面进行分析和研究。 相似文献
8.
动力环境网络监控精细管理 总被引:1,自引:0,他引:1
叙述动力环境运行质量分析管理,包括故障管理,性能管理和专题分析管理,以动力环境网络监控细致八微、言之有据的月度分析管理实例展现了其精细管理的效果。 相似文献
9.
通过比较各种软件无线电结构的优缺点,针对既具有交换网络结构又具有分层结构优点的基于交换网络的分层无线电结构方案,提出了部分改进思想。 相似文献
10.
从"天人合一"到"物我合一"——设计艺术中我国观念的转化 总被引:1,自引:1,他引:0
通过我国设计艺术中人与自然以及人与物古今观念的对比,试图分析这种观念的转化产生的深层社会背景和对设计的影响。 相似文献